irc: remove unneeded error message when an unknown server option is read in config file (issue #1039)

This is not needed because an error is already displayed by WeeChat core and
the IRC error doesn't add anything relevant to the user.

src/plugins/irc/irc-config.c

@@ -2799,14 +2799,6 @@ irc_config_server_read_cb (const void *pointer, void *data,
         }
     }
 
-    if (rc == WEECHAT_CONFIG_OPTION_SET_ERROR)
-    {
-        weechat_printf (
-            NULL,
-            _("%s%s: error creating server option \"%s\""),
-            weechat_prefix ("error"), IRC_PLUGIN_NAME, option_name);
-    }
-
     return rc;
 }